Glaciology
In recent years, there has been particular focus on changes in the dynamics of ice flows, glaciers and ice shelves. These changes are to a large degree the result of the pronounced melting, retreat and break-up of the ice, a pattern that has been replicated globally within a range of glaciers and icecaps. Pronounced changes in the dynamics of the Inland Ice and the glaciers in Greenland have also been registered, as illustrated by the Ilulissat Glacier. The flow rate of this glacier has almost doubled (to 13 km/year) since 1997. In this connection, the Ilulissat Icefjord and Disko Bay are unique areas of study, as the advances and retreats of the glacier front have been documented in detail since 1850. These glacier front changes are reflected in the distribution of Inuit settlements along the fjord. New model studies show that a possible response by Greenland’s ice cap to continued global warming will be an acceleration of the glaciers’ speed, displacement of the glaciers’ front on to the shelf and an increase in the production of icebergs. To be able to predict the response of the ice cap to global warming, it is necessary to understand the factors that control these movements. It has been shown that changes in the dynamics of a glacier front can quickly propagate upstream and have a pronounced effect on the drawdown of ice, which occurs from the ice cap to the oceans. This increase in the outflow of glacial ice to the oceans influences both the global sea level and the flux of freshwater to the oceans. At Ilulissat, however, it has been shown, that a temperature increase in the area at the start of the 1900s did not influence the location of the glacier front. It is therefore unclear whether this ‘insensitivity’ was the result of a delay in the climate/ice/ocean system response to the change in temperature, or if the present sudden change is due to completely different factors. To determine possible factors affecting the stability of a glacier, the advances and retreats of the glacier over a longer period of time must be surveyed and put into the context of previous climatic variations, as reflected in sediment cores.
|
|
|
